JPS6352453A - Forming method for leads of semiconductor device - Google Patents

Abstract

PURPOSE:To prevent IC leads from being laterally warped (bent) by providing a guide block formed integrally with the upper surface of a bending die. CONSTITUTION:A guide block 13 is provided on the surface (upper surface) of the bending die 12 of a lower mold 11 oppositely to a first bending punch 112, and the leads of an IC inserted to the metal mold are set. That is, the block 13 projected on the upper surface of the die buries leads of the inserted IC to suppress the drooping of the leads generated at the time of forming the leads to forcibly hold the normal shape. Thus, the lead drooping generated unavoidably in the step of forming the leads is prevented by providing the block 13 integrally with the die.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Field of Application) The present invention is directed to a lead forming method for a semiconductor device, and is applied to a lead forming method using a lead frame and sealing the lead frame with resin. be done.

(Prior Art) A mold used for molding leads of a semiconductor device (hereinafter referred to as an IC) formed by resin sealing using a lead frame will be shown in the third article. In FIG. 3, 101 is a lower die, which is a flat bending die 10 that supports and shapes the tip of the lead.
2 is fixed to the lower die holder 104 via the side plate 103, and - a pressure pad 106 which is vertically slidable in the center of the bending die 102 and supported by a spring 105 bends the upper die as described below. Together with the punch, it supports the resin sealing part and the leads protruding from it.

Next, the first bending punch 112, which faces the bending die 102 and supports and shapes the tip of the lead, passes through the side plate 113 to the upper die holder 11.
4, a second bending punch 116 that is vertically slidable in the center of the first bending punch 112 and supported by a spring 115 is attached to the pressure pad 106 of the lower die and the resin of the IC. Supports the sealing part and the leads protruding from it.

The above-mentioned upper mold] and lower mold 101 achieve molding of IC leads into a desired shape by vertical movement of a press machine.

Further, the spring 105 of the lower mold absorbs pressure during molding, and the spring 115 of the upper mold prevents the IC from sticking to the second bending punch 106 during lead molding.

Note that the lead frame used in the above IC has a very narrow gap between the leads, so when the lead frame is manufactured by punching (cutting) using a mold whose main parts are shown in Figure 4, the punching process for the lead part is 1. Perform two steps for every pitch. 1 in Figure 4
21 is a cutting punch, 123 is a cutting die, and 122 is a stripper. The lead frame material 100 is inserted between the cutting punch 121 and the cutting die 123. First, leads are formed by punching every other pitch, and then these leads are The formation of all the leads at a predetermined pitch is achieved by punching the leads at each intermediate point.

(Problems to be Solved by the Invention) According to the conventional lead forming method described above, an unavoidable lateral sag (bending) occurs during lead forming.

As mentioned above, when performing processing (cutting, punching, etc.) between the leads using a die, the lead formation is performed in two steps, as an example, but the conditions during the first processing step, that is, the cutting The clearance between the punch 121 and the cutting die 123, the setting position of the lead frame material 100, etc. cannot be obtained exactly the same in the secondary processing step, and because a relatively soft material such as copper is used, the fifth The deformation is as shown in the front view of the cut surface of the lead portion 100a of the lead frame material viewed from the cut surface side. Punching (
Unless the cutting surface has a symmetrical shape, it is inevitable that the lead will bend in the direction with less droop.

An object of the present invention is to provide a lead forming method that prevents bending of the leads when forming the lead portions of a lead frame having a structure in the lead portions as described above.

[Structure of the invention]

(Means for Solving the Problem) A lead forming method for a semiconductor device according to the present invention includes a lead forming step in which a lead frame with narrow lead intervals is punched and formed in several steps using a cutting die.

and a lower die including a pressure pad and a bending die provided with a guide block, an upper die including a first bending punch corresponding to the pressure pad, and a second bending punch corresponding to the bending die. The present invention is characterized by comprising a lead bending step in which the lead frame is inserted between the lead forming molds and the leads thereof are placed between the guide blocks and bent.

(Function) According to the present invention, a guide block is provided integrally with the bending die to completely prevent the lead from sagging (bending) which inevitably occurs during the lead forming process.

(Embodiments) Embodiments of the present invention will be explained below with reference to the drawings. In the description, parts that are the same as the conventional ones will be denoted by the same reference numerals as the conventional ones in the drawings, and the explanation will be omitted.

In FIG. 1 in which the mold of one embodiment is rotated, the bending die 12 of the lower mold 11 is provided with a guide block 13 on the surface (upper surface) facing the first bending punch 112, and the IC inserted into the mold is
Set the lead. That is, the guide block 13 protruding from the upper surface of the bending die fills the space between the leads of the inserted IC, suppresses the lateral sagging (bending) of the leads that occurs during lead molding, and forcibly maintains the normal shape.

Note that the guide block is longer than that illustrated in the first M,
For example, it may be formed in a guide block 23 as shown in the front view in FIG.

[Effects of the Invention] According to the present invention, the guide block integrally formed on the upper surface of the bending die can completely prevent horizontal sagging (bending) of the machining C lead.

This will greatly improve work efficiency and productivity, as well as improve IC process yield. Also.

Product reliability increases. Next, even if the limit on lead frame production is reduced, lateral sag (bending) during lead molding can be prevented, and manufacturing yields, quality, etc. can be maintained at a good level, which is a remarkable advantage.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a mold used in one embodiment of the invention, FIG. 2 is a top view of a lower mold of another embodiment of the invention, and FIG.
FIG. 4 is a cross-sectional view illustrating the punching process for lead frame processing, and FIG. 5 is a front view of a cutaway view of the lead viewed from the cut surface side. ■...Lower die 12...Bending die

Claims (1)

[Claims] A lead forming process in which a lead frame with a narrow lead interval is punched and formed in several steps using a cutting die, a lower die equipped with a bending die equipped with a pressure pad and a guide block, and a pressure pad formed on the pressure pad. The lead frame is inserted between a lead forming mold consisting of an upper mold having a corresponding first bending punch and a second bending punch corresponding to the bending die, with the leads thereof being placed between the guide blocks. A semiconductor device lead forming method including a lead bending step.